System for supplying an emulsion of liquid fuel and water to a heating burner

ABSTRACT

A process and system for supplying an emulsion of liquid fuel and water to a burner capable of operating at a low heating rate and at least another higher heating rate. After stopping the normal heating and for re-igniting the burner, a part of the burner is connected to discharge to the fuel tank without pressure and the burner is first supplied with liquid fuel alone under pressure so as to expel the emulsion which filled the burner when the burner extinguished. The burner filled with liquid fuel alone is ignited and then supplied with the emulsion in accordance with the desired heating rate.

United States Patent r191 Delatronchette et al.

[ Oct. 23, 1973 SYSTEM FOR SUPPLYING AN EMULSION OF LIQUID FUEL AND WATER TO A HEATING BURNER [75] Inventors: Claude Delatronchette, Cachan;

Raymond Hltou, Clamart, both of France; Ren Gunthart, Geneva; Andr Meissner, Vernier, both of .1 a witw n [73] Assignee: Elf Union and Ateliers Des Charmilles S.A., Paris, France and Chatelain-Geneve (Swiss) [22] Filed: June 1,1971

[21] Appl. No.: 148,444

[30] Foreign Application Priority Data June 2, 1970 France 7020190 [5 6] References Cited UNITED STATES PATENTS 2,033,010 Russell 431/4 2,104,311 1/1938 Russell 431/4 2,818,110 12/1957 Rulseh 3,358,735 12/1967 Luft 431/29 Primary ExaminerWilliam R. Cline Attorney.lohn Lezdey, Robert Osann, Jack F. Kramer, Julius Balogh and George F. Dvorak 57] ABSTRACT A process and system for supplying an emulsion of liquid fuel and water to a burner capable of operating at a low heating rate and at least another higher heating rate. After stopping the normal heating and for reigniting the burner, a part of the burner is connected to discharge to the fuel tank without pressure and the burner is first supplied with liquid fuel alone under pressure so 'as to expel the emulsion which filled the burner when the burner extinguished. The burner filled with liquid fuel alone is ignited and then supplied with the emulsion in accordance with the desired heating rate.

4 Claims, 2 Drawing Figures SYSTEM FOR SUPPLYING AN EMULSION OF LIQUID FUEL AND WATER TO A HEATING BURNER The present invention relates to the heating of furnaces, boilers or other apparatuses with an emulsion of light or heavy fuel-oil or other liquid fuel and water by means of an automatic heating burner having one or more heating rates or a variable heating rate.

Many trials have been carried out for such a heating process but up to the present time the results obtained have been particularly disappointing. Indeed, although the utilization of an emulsion of liquid fuel and water is very advantageous as concerns the combustion rate (the utilization of a certain percentage of water permits a considerable decrease in the excess air and the amount of solid unburnt elements which gives a practically zero smoke or fumes index), the trials have shown that after the heating has stopped, a new starting up directly with the emulsion employed under normal conditions presents serious difficulties. Indeed, theignition is obtained in only 80 percent of the cases, which is of course unacceptable in automatic systems (industrial or domestic burners).

An object of the present invention is to remedy this serious defect.

The invention provides a process for supplying an emulsion of liquid fuel and water to a heating burner which permits, in particular, completely reliable ignitions of the burner with no possibility of failure.

The process according to the invention comprises employing a burner capable of operating at a low heating rate and at least another higher heating rate and, after a stopping of the normal heating with an emulsion of liquid fuel and water supplied to the burner, connecting at least a part of the burner to the discharge, without pressure, to the source of liquid fuel and supplying the burner with liquid fuel alone under pressure so asto expel the emulsion of fuel and water which filled the burner when the burner extinquished and fill the burner with liquid fuel along with which, after closing the discharge, the burner is re-ignited before resuming the normal supply of the emulsion of liquid fuel and water to the burner in accordance with the desired heating rate.

According to one embodiment, a burner is employed having two jets one of which affords the low heating rate and both of which afford a higher heating rate and the jet which affords the low heating rate is the jet which is connected to the discharge.

According to another embodiment, a burner is employed having a single jet arranged to effect a flow modulation and it is this single jet which is connected to the discharge.

Another object of the invention is to provide a heating system adapted to carry out the process defined hereinbefore.

The heating system according to the invention comprises, in combination with a burner capable of operating at a low heating rate and at least another higher heating rate: two supply circuits under pressure, a first of said circuit supplying liquid fuel and a second of said circuits supplying water, the first circuit comprising a liquid fuel tank; a mixer producing an emulsion of liquid fuel and water to which the two circuits are connected; a pump having an inlet connected to the mixer and an outlet connected to the burner for delivering the emulsion under pressure; a discharge conduit connecting at least one part of the burner to the liquid fuel tank; and two electrically-operated valves, a first of said valves being inserted in the water circuit on the inlet side of the mixer, a second of said valves being inserted in the discharge conduit of the burner, the first valve being of the type normally closed and the second valve being of the type normally open so that the first valve is closed and the second valve is open when the heating is stopped and the first valve is open and the second valve closed during the heating.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompaning drawings:

In the drawings:

FIGS. 1 and 2 are diagrammatic views, with various devices shown partly in section, of two heating systems according to the invention, these systems being shown with the electrically-operated valves in the positions they occupy after stoppage of the heating and prior to closure of the electrically-operated discharge valve combined with the burner, the latter having two jets in FIG. 1, a single modulating jet in FIG. 2.

In the embodiment shown in FIG. 1, the system is adapted to heat a furnace or other apparatus A with an emulsion of liquid fuel, in particular a heavy or light fuel-oil, and water by means of a burner B having two jets or nozzles, the jet or nozzle 1 pertaining to the low heating rate and the jet or nozzle 2 pertaining to a higher heating rate and being connected in parallel with the first jet.

The heating system comprises three circuits, namely:

a circuit I supplying liquid fuel shown in full line of medium thickness;

a circuit II supplying water shown by two lines drawn closely together; and

a circuit III delivering the liquid fuel alone or an emulsion of fuel and water, this circuit III being shown in thick black line.

The two circuits I and II supplying liquid fuel and water respectively are connected to a mixer-emulsifier 3 to which the inlet of a pump 4 is also connected. The pump 4 delivers the emulsion to a circuit 5 which is divided into two branches 5 and 5" connected to the jets l and 2 respectively.

The liquid fuel supply circuit 1 connects a tank 6, or other source of liquid fuel at atmospheric pressure, to the mixer-emulsifier 3. A pump 7 has its inlet located adjacent the base of the tank and draws in fuel through a filter 8 and delivers the fuel to a forced-feed loop comprising two conduits 9 and 10 connected by a pressure regulating valve 11 whereby it is possible to maintain in the conduit 9 a given pressure while the conduit 10 of the loop returns fuel to the tank 6 at 12. Connected to the pressure conduit 9 of the forced feed loop is a liquid fuel heater 13 provided with a drain 14. The outlet of the heater 13 is connected by a conduit 15 to the inlet 16 of the mixer-emulsifier 3.

The water supply circuit II connects a water mains 17 under pressure to the mixer-emulsifier 3 in the following manner: connected to the mains 17 is a conduit 18 which leads through a cock 19 to a filter 20 connected to a stabilizing pressure reducing valve 21. The outlet of the valve 21 is connected to two circuits in parallel, namely, a circuit 22 having a low-flow pressure reducing valve 23 and a circuit 24 having therein in series relation an electrically operated valve 25 and a high flow pressure reducing valve 26, the valve 25 is of the type normally closed (it is closed in the absence of current in its coil 27 which has its terminals a and b connected to an electric supply, not shown.

The two parallel circuits 22 and 24 are connected to a flowmeter 28 whose outlet is connected to a water heater 29. There is provided between the flowmeter 28 and the heater 29 a relief valve 30 adapted to compensate for or accommodate the expansion of the water in the heater 29. The latter is provided with a drain 31 and a conduit 32 in which is provided a check valve 33 connecting the heater 29 to an electrically operated valve 35 also of the normally closed type (the valve is closed when its coil 36 does not receive at its terminals and d an electric energizing current). The outlet of the valve 35 is connected to the mixer-emulsifier 3 at 37.

As concerns the circuit III corresponding to the delivery side of the pump 4, there is connected in the conduit 5 which leads to the high heating rate jet an electrically-operated valve 38 of the normally closed type (the coil 39 of the valve opens the valve when it is energized by current supplied to its terminals a and b In other words, the valve 38 and the valve 25 can be connected to the same supply terminals of an electric supply system.

The branch 5 of the circuit III is directly connectd to the cavity defined by the low heating rate jet 1 but this cavity is connected to the pressure-free branch of the forced-feed loop (9,10) by a conduit 40 in which is inserted an electrically-operated valve 41 of the normally open type (its coil 42 closes the valve when energized by supply of current to the terminals 0 and d).

These supply terminals 0 and d of the valve 41 can therefore be connected to the same terminals of the supply system as the coil 36 of the valve 35, but, as these valves are operative in opposite directions, in the absence of current valve 35 is closed and valve 41 is open. Valve 35 is open and valve 41 is closed when these valves are supplied with current.

The system operates in the following manner:

After a voluntary or accidental stopping of the system with the pump 4 inoperative and the valves in the illustrated positions, a new starting up of the system requires the following successive operations:

ventilation of the interior of the boiler or other heating apparatus A to avoid any danger of explosion;

starting up of the pumps 7 and 4 and circulation of the liquid fuel in the circuit: heater 13, conduit 15, mixer 3, pump 4, conduit 5, branch 5", low heating rate jet 1, open discharge valve 41, conduit 40, discharge branch 10 of the forced-feed loop, tank 6; the high heating rate jet 2 is cut off from the circuit III by the as a result of the opening of the valve 35 water is injected through the circuit 17 18 19 20 21 23 28 29 32 35 37; in addition to the increased pressure of the fuel in the jet 1, the water circuit is put into communication with the mixer 3; thenceforth, the pump 4 delivers a fuel-water emulsion which follows on the pure fuel filling the conduit 5 and the jet 1 and soon replaces this pure fuel in the stream issuing from the jet 1; the latter thenceforth affords the normal heating at a low rate;

passage to the high heating rate ensured by the simultaneous opening of the valves and 38; the valve 25 valve 38 which is closed; the circulation of the fuel alone has for effect to expel the emulsion which had remained in the low heating rate jet 1 and return it to the fuel tank 6: this is a fundamental feature of the present invention and has the important advantage of allowing thereafter an initial supply of the fuel alone upon the starting up of a new heating cycle;

closure of the valve 41 and simultaneous opening of the valve 35; this raises the pressure of the fuel in the jet 1; fuel devoid of any emulsion with water is therefore initially ejected from this jet so that the ignition occurs with pure fuel and consequently with absolute reliability which would not be possible, as mentioned hereinbefore, if an emulsion where attempted to be ignited;

permits supplying water via the branch circuit 24 and the high-flow pressure reducing valve 26, whereas the opening of the valve 38 permits supplying the jet 2 with emulsion while the jet 1 continues of course to be supplied; the supply rates of flow increase up to the high heating rate.

Reference will now be made to the heating system shown in FIG. 2 in which the burner has only a single jet or nozzle 1 of the flow modulating type.

This system is on the whole very similar to the system shown in FIG. 1 and includes the three circuits 1, II and III and the various devices designated by identical reference characters.

The liquid fuel supply circuit I is identical to that of the first embodiment. As concerns the water supply circuit II", it does not include a branch connection 24, 25, 26 of the circuit II of the first embodiment. The circuit III has only one conduit 5 connecting the outlet of the pump 4 to the cavity defined by the flow modulating jet 1.

The jet 1 is combined with means for modulating the heating rate; they are diagrammatically represented by a conduit 43 connecting the outlet of the jet to the mixer 3 and a pressur regulator 44 is inserted in the conduit 43 and has a modulating control of known type.

The system shown in FIG. 2 operates in a manner similar to the invention shown in FIG. 1.

After a voluntary or accidental stopping of the system, with the pumps 4 and 7 inoperative and the valves in the illustrated positions, a starting up of the system comprises the following sucessive operations:

ventilation of the interior of the boiler or other heating apparatus A so as to avoid any danger of explosion; starting up of the pumps 7 and 4 to cause the liquid fuel to circulate through the circuit: filter 8, pump 7, heater 13, conduit 15, mixer 3, pump 4, conduit 5, cavity of the jet 1", open discharge valve 41, conduit 40, discharge branch 10 of the forced-feed loop, tank 6; the circulation of fuel alone has for effect to expel the emulsion which had remained in the jet 1 and return it to the fuel tank 6;

closure of the valve 41 and simultaneous opening of the valve 35; this causes the pressure of the fuel in the jet 1 to rise; fuel devoid of any water issues from this jet and the ignition occurs with pure fuel; owing to the opening of the valve 35, water is injected via the circuit 17-18- 19-20-21 -23-2829-3235;the pressure of the fuel increases in the jet 1 and the water is supplied to the mixer 3; thenceforth the pump 4 delivers a fuel-water emulsion which follows on the pure fuel which fills the conduit 5 and the jet 1 so that this emulsion soon replaces this pure fuel in the stream issuing from the jet 1.

The rate of flow through the jet 1 is modulated by the pressure regulator 44.

Having now described our invention what we claim and desire to secure by Letters Patent is:

1. In a system for supplying an emulsion of liquid fuel and water to a first heating burner nozzle which defines a cavity receiving the emulsion and having an inlet, comprising pressurized liquid fuel supply means including a liquid fuel tank, pressurized water supply means emulsifying means having two inlets respectively connected to the fuel supply means and water supply means and an outlet, an a pump having an inlet connected to the outlet of the emulsifying means and an outlet connected to the inlet of the nozzle; the provision of a fuel discharge outlet in the nozzle, a discharge conduit disposed between the outlet of the first nozzle and the tank, a first valve in the conduit, said first valve being in an open position at the start up of the system, a second valve in the water supply means and being in a closed position at the start up of the system, means connected to the first valve and the second valve for substantially simultaneously closing the first valve and opening up the second valve after the pump has been started up, whereby to permit automatically first expelling the fuel and water emulsion from the nozzle cavity by way of said conduit and supplying instead solely the liquid fuel to the nozzle cavity upon starting up the pump when starting up the burner and thereyby facilitate ignition of the nozzle and thereafter allowing said emulsion to be supplied to the nozzle by substantially simultaneous closure of the first valve means and opening of the second valve means.

2. A system as defined in claim 1 in which the burner further comprises a second nozzle, said first nozzle affording a low rate of heating and said second nozzle affording, in combination with said first nozzle, a high rate of heating, said second nozzle having an emulsion inlet, and second means disposed between said emulsion inlet of the second nozzle and said pump for putting the inlet of the first nozzle and the inlet of the second nozzle in communication with the outlet of the pump.

3. A system as defined in claim 1, further comprising flow modulating means disposed between the outlet of said pump and the inlet of said first nozzle and the modulating the flow of emulsion through the first nozzle.

4. A system as defined in claim 1, wherein said liquid fuel supply means has a second pump with an inlet connected to said tank and an outlet, means connecting the outlet of the second pump to the corresponding inlet of the emulsifying means, a forced-feed loop circuit connecting said outlet of said second pump to said tank, a fuel pressure regulator in said loop circuit, said discharge conduit being connected to said loop circuit be tween said pressure regulator and said tank. 

1. In a system for supplying an emulsion of liquid fuel and water to a first heating burner nozzle which defines a cavity receiving the emulsion and having an inlet, comprising pressurized liquid fuel supply means including a liquid fuel tank, pressurized water supply means emulsifying means having two inlets respectively connected to the fuel supply means and water supply means and an outlet, and a pump having an inlet connected to the outlet of the emulsifying means and an outlet connected to the inlet of the nozzle; the provision of a fuel discharge outlet in the nozzle, a dischArge conduit disposed between the outlet of the first nozzle and the tank, a first valve in the conduit, said first valve being in an open position at the start up of the system, a second valve in the water supply means and being in a closed position at the start up of the system, means connected to the first valve and the second valve for substantially simultaneously closing the first valve and opening up the second valve after the pump has been started up, whereby to permit automatically first expelling the fuel and water emulsion from the nozzle cavity by way of said conduit and supplying instead solely the liquid fuel to the nozzle cavity upon starting up the pump when starting up the burner and thereby facilitate ignition of the nozzle and thereafter allowing said emulsion to be supplied to the nozzle by substantially simultaneous closure of the first valve means and opening of the second valve means.
 2. A system as defined in claim 1 in which the burner further comprises a second nozzle, said first nozzle affording a low rate of heating and said second nozzle affording, in combination with said first nozzle, a high rate of heating, said second nozzle having an emulsion inlet, and second means disposed between said emulsion inlet of the second nozzle and said pump for putting the inlet of the first nozzle and the inlet of the second nozzle in communication with the outlet of the pump.
 3. A system as defined in claim 1, further comprising flow modulating means disposed between the outlet of said pump and the inlet of said first nozzle and modulating the flow of emulsion through the first nozzle.
 4. A system as defined in claim 1, wherein said liquid fuel supply means has a second pump with an inlet connected to said tank and an outlet, means connecting the outlet of the second pump to the corresponding inlet of the emulsifying means, a forced-feed loop circuit connecting said outlet of said second pump to said tank, a fuel pressure regulator in said loop circuit, said discharge conduit being connected to said loop circuit between said pressure regulator and said tank. 